Compare data SQL statements from two tables in MySQL

There are two tables T_appinfo and g_appinfo, the stored information is basically consistent, all contain package_name this field, now need to find out package_name exists in the T_appinfo table, and does not exist in the G_appinfo table records.

Method One: Use Not EXISTS

The code is as follows	Copy Code
SELECT A.name,a.package_name from T_appinfo a WHERE not EXISTS (SELECT 1 from G_appinfo g where a.package_name=g.p_packagename) LIMIT 10000

Method Two: Use Not in

The code is as follows	Copy Code
Select A.name, a.package_name from T_appinfo a WHERE a.package_name not in (SELECT g.p_packagename from G_appinfo g) LIMIT 50000

When two tables have more data, for example, more than 100,000, you need to add index to package_name, improve query efficiency.